n0021576

A "no codes" problem! Motor cranks fine, but over the last few weeks it has randomly been napping when trying to start. Occasionally, the first attempt on a cold motor results in it not starting. It then fires on the second attempt. No codes. It also has refused to start on occasion when hot. On Sunday I made 4-5 stops with no problem. It would not start after the last stop. Waited 45 minutes before it fired. Determined the fuel pump was not spooling up. I changed out the fuel pump relay, PCM relay and cleaned up the battery and grounds under the hood. It eventually fired, but I don't know if it was because something is cooling off, resetting, or knows I am going to hunt it down and kill it. The beast did it again last night, this time fortunately in my garage 5 minutes after coming home from work. I tried both PATS keys and the same thing happened - crank but no start. As luck would have it, by the time I tried to check power to the fuel pump, I was getting a reading. It fired up, so I don't know for sure if it is voltage to the pump or the pump is the problem Did I mention NO CODES? AARGH!

The theft light appears to be acting normally.

I've been bouncing through a few threads here and on other sites. I have heard everything from replacing fuel pumps (this has 118K miles - is it time?) to PCM relays, to crank sensors. Anyone confident on where to start? A crank sensor at NAPA is $29 and a fuel pump might be good insurance on a truck that needs to go another 60K miles.

I'm a newbie over here (spent too much time at the Mustang forum), so pardon me if this thread has been kicked around before.

BigIrish

Rent a fuel pressure gauge and replace the fuel filter. Its probably past time for the fuel filter, and after replacement, the gauge will help you verify pressure to the rails.

The service history on my truck indicates it ate two pumps so far in its life, one at around 180k miles (original pump failure, due to age) and another less then 10k miles later (defective pump, warrantied out). Crank, no start no code is usually a fuel pump or filter problem.

n0021576

Thanks for the quick response! I should have posted I did check the fuel pressure off the Schrader valve on the fuel rail. Good pressure when it had been running just before the check and no pressure after it had its no-start tantrum and the pump would not spool up. NAPA has a fuel pump for $179. Certainly cheaper than having to tow it and THEN put a pump in it.

My01SCrew

Sounds similar to when my PCM went out, it wouldn't read any codes from the PCM, started when it wanted to. Ended up costing a grand after all was said and done. That's including cost of the pump and filter that I changed. If you take it to the dealership be prepared to spend a few hundred on diagnostic. Good Luck.

BigIrish

Did you replace the fuel filter? Its cheap and easy, and probably the most neglected service item on a vehicle. A over used filter clogs and causes all sorts of issues. This makes it worth a try before you go through the hassle of the pump swap.

Edit: I think PCM failure can be easily diagnosed by plugging in any OBD2 scanner into the OBD2 port. I think a bad computer registers as either key off or incompatible device on a scanner.

My01SCrew

It threw no codes with the scanner at autozone and when I took it to the dealership they couldn't figure out what was wrong with it initially, even tried telling me that it was sending the correct pressure to the rails when I had watched it multiple times with a gauge and saw that it wasn't.

I'm not saying for sure that its the same fault as I had, just that I had similar symptoms and dropped the tank for no reason.

Good old Bill

You know the answer, no pressure during the no start, is the pump and or wiring. I recently replaced my pump for this same reason. I had a problem with a leak after I was done, didn't get the pump tight enough to the tank, leaked at seal. I am confessing my error to disclose the easier way to replace the pump. Take off the bed, 6 bolts, 1 connecgtor to tail lights, and the filler pipe loose at body. Lift it off, block it up, what ever. Now you can test for voltage, replaced pump, and check for leaks, at the same time.

rcantu

pump isn't accessible via bed in a supercrew. the only model that can't.

My01SCrew

When I dropped mine it wasn't to bad. Just make sure you have the right line release tools, vent lines were a kind of a p.i.t.a. to remove. I used stacks of bricks to drop it because I didn't have a floor jack. It's really not that bad of a job, I'd say its a 6 pack job any more than that and you're drinking more than working.

n0021576

I have an Acton OBD II scanner on the front seat and checked it every time it failed. No codes....ever. All I know is the pump wasn't powering up during no start. I had a PCM failure on an older F150 (it got wet) and that one wouldn't spit a code either. I think sometimes we rely too much on these blasted scanners.

I'm doing preventive maintenance at this point. I put a crank sensor in it last night (45 minute job) and it fired up 20 times in a row, eliminating the first crank-no fire problem. I don't think that is the real issue, so I bought a pump and filter.

Thanks for all of your input- it gets the brain thinking. One thing I'll share in return is I changed the dual tanks on my old F150, a 90 XR7,a 62 T bird, a 54 Merc, 54 F100, my street rod a couple of times (@#$%!!!), etc. One of the easiest ways to pull a tank is to use cargo straps. You can use the ratchet to ease the tank down without worrying about the tank sliding off of a board on a jack or denting the tank. You can also drop the tank flat on the ground without worrying if the tank is going to slide off the jack or clear the body.